The present invention relates to carpentry tools and more particularly to a combination wrench with adjustable heads which can be automatically adjusted to consist with the size of an object such as a nut to which it rotates.
People usually use different sizes of combination wrenches to work at different sized nut which is uneconomical. A typical adjustable combination wrench (as shown in FIG. 1) is thus worked out which comprises a handle 1 and a pair of rotatable boxes 3 of irregular hexgon pivoted at two ends of the handle 1. The handle 1 has a jaw 2 at each ends. When engages the box 3 with a working object such as a hexgon nut and rotates the handle 1, the jaw 2 presses a side of the object to reduce the size of the box 3 in order to fit the shape of the object and further to faster or unfasten the object. This type of combination wrench provides a limited range to fit some of the hexgon nuts. However, it has the advantages set forth as follows:
a) because of a greater wondering clearance, it causes a free run which damages or deforms the working object, PA1 b) the repeated engagement and/or disengagement with the object requires a rotation angle that greater the 60.degree. which causes an operation limitation to the user, and PA1 c) it does not fit a small working object or operate within a small space.